Turnover studies in man have been very successful in providing reasonable explanations of important clinical phenomena. This research proposal is concerned with: (1) using 15N glycine as a tracer to study human whole body and plasma protein synthesis rates and (2) using deuterium labelled saturated fatty acids to study lipid turnover. The project is concerned with developing methods and then applying them to such problems as the effect of 5-FU on human protein metabolism and intravenous hyperalimentation on human lipid metabolism.